(1) Field of the Invention
The present invention pertains to the automated testing of a telephone switching center and more particularly to a call processing monitor system for continually initiating telephone calls and detecting whether each call was properly completed.
(2) Description of the Prior Art
In present date telephony, switching systems are implemented with complex configurations of hardware and software elements. Such switching systems are computer controlled systems and many of such systems have multiprocessor configurations. Each switching system has software which monitors various hardware operations and initiates alarms for the detection of any faults. In a similar fashion, specialized hardware is implemented in order to detect certain software faults.
It is of particular importance to detect those hardware and latent software faults which affect the switching function of a telephone switching center. However, certain faults may go unrecognized or if recognized the system may be incapable of initiating the proper alarm. These faults may inhibit the processing of telephone calls for extended periods of time. Typically, modern switching centers are unattended for substantial periods of time. Thereby, faults which affect the call processing function of the switching center may go undetected. Such switching systems may include No. 1 EAX and No. 2 EAX manufactured by GTE Automatic Electric Inc.
Initially, methods of detecting a call processing service outage consisted of an operator at another office being unable to complete a call to the service affected switching center or a customer who reports the switching center outage from another switching center. Such methods are inadequate and thereby, a community may be without telephone service for an extended period of time.
A partial solution to the problem is taught by U.S. Pat. No. 4,021,624 issued on May 3, 1977, to P. M. Kelly et al, which teaches an automatic call generator which attempts to place calls from one dedicated spot to another. This system employs complex logic and a central processing unit including 16 programs which operate this system.
Another complex solution is taught by U.S. Pat. No. 3,692,962 issued on Sept. 19, 1972, to J. R. Raczynski et al, which teaches an array of up to 5 automatic dialing devices operating independent of one another and producing a count of attempts and failures of each dialing device.
Two other systems which employ computer control for automatic call generation are taught in U.S. Pat. Nos. 3,952,172, issued on Apr. 20, 1976, to C. J. L. Penn et al, and 3,692,961, issued on Sept. 19, 1972, to G. J. LeStrat et al.
Therefore, it is the object of the present invention to provide a call processing monitor system which monitors the call processing ability of a switching center in a simple and economical fashion and provides an alarm output when a particular failure pattern is detected.
It is a feature of the present invention to provide the above mentioned objective without a central processing unit and any operating software which itself may contain latent errors.
It is another feature of the present invention to provide a self-contained unit independent of the switching center to which it is connected.
It is another feature of the present invention to provide alarm outputs which may be transmitted to a remote location.